1. Field of the Invention
The present invention relates to a video image coding data transmission technology and, more particularly, to a video image coding data transmission technology for transmitting video image coding data in real time.
2. Description of the Related Art
In recent years, services for compression-coding content such as video images, sounds, and the like and transmitting compression-coded content in real time through a network have been growing with the improvement of the performance of mobile terminals such as smartphones and the like, the extension of a network band due to the introduction of LTE and the like, and the progress of a video image compression coding technology such as HEVC and the like.
In a network such as the Internet (IP network), best-effort type transmission is performed, and a band is not guaranteed. Therefore, a transmission rate changes depending on the number of users, the location of use, and the like. Further, in a wireless network, the network can be temporarily disconnected.
Therefore, TCP, which provides quality assurance such as retransmission control, is used in non-real time data transmission. However, quality assurance involving retransmission control is accompanied with delay and is thus not suitable for real-time data transmission. UDP, which does not provide quality assurance, is used in real-time data transmission. Conventional technologies for transmitting video images in real time are disclosed in, for example, Patent document No. 1 and Patent document No. 2.
[Patent document No. 1] Japanese Patent Application Publication No. 2005-303925
[Patent document No. 2] Japanese Patent Application Publication No. 2008-199677
However, a method described in Patent document No. 1 represents a technology where data selected by thinning selection is transmitted in real time and unselected data that has not been transmitted is then transmitted. Thus, a problem with this is that real-time video image transmission and viewing of high-quality video images cannot be achieved at the same time. Also, in a method described in Patent document No. 2, a single video image is duplicated for highly-compressed video image data and low-compressed video image data and transmitted. Thus, a decrease in transmission efficiency becomes a problem.